American Factfinder. The Census Bureau's gateway to data, including geographic data.
CIA World Factbook. A one-stop source for basic data on foreign nations.
Geodata.gov. Geodata.gov is a geographic information system (GIS) portal, also known as the Geospatial One-Stop (GOS), that serves as a public gateway for improving access to geospatial information and data.
Geonames.usgs.gov/domestic. Geographic names authority and gazetteer for the nation.
NationalAtlas.gov. This is the best federal source for national maps and geographic information on the Web.
National Map. The National Map is a collaborative effort among the USGS and other Federal, State, and local partners to improve and deliver topographic information for the Nation. It has many uses ranging from recreation to scientific analysis to emergency response.
Ngtoc.usgs.gov/girt. Geospatial information for effective emergency response.